As is well known in the art, in recent years, there is a demand for further thinning of various glass plates including glass substrates for a flat panel display, such as a liquid crystal display, a plasma display, an organic light-emitting diode (OLED) display, or a field emission display. Along with the demand for the further thinning, as disclosed, for example, in Patent Literature 1, a film-like sheet glass having a thickness of 200 μm or less has been developed.
Further, as disclosed, for example, in Patent Literature 2, as a package form for the above-mentioned sheet glass thinned into a film (hereinafter, referred to as glass film), there is adopted a glass roll formed by winding the glass film into a roll around a roll core while the glass film is superposed on an intermediate layer. The package form utilizes a characteristic that the glass film has sufficient flexibility due to its thinness.
On the other hand, the glass film has a shortcoming that the glass film is likely to break due to its thinness. Therefore, as disclosed in Patent Literature 2, even in a case of adopting the glass roll as a package form for a glass film, there is a problem that remains to be solved.
The problem is as follows. That is, when the glass roll is placed on a placed surface such as a pallet while the roll core is arranged in a laid posture, i.e., a substantially horizontal posture, the glass film is held in contact with the placed surface through the intermediate layer, and hence concentration of stress occurs on the contact portion of the glass film. Consequently, the glass film easily breaks.
In this context, in order to cope with the above-mentioned problem, a package form for a pressure measuring sheet disclosed in Patent Literature 3 may be applicable, though Patent Literature 3 does not relate to the glass film. That is, Patent Literature 3 discloses a package form, in which a flange larger in size than an outer diameter of the wound pressure measuring sheet is provided at each end of a roll core around which the pressure measuring sheet is wound, and the pressure measuring sheet is separated from the placed surface.